U.S. Pat. No. 4,811,372 discloses X-ray equipment in which a plate that is mounted via roller bearings on a supporting plate is capable of being moved through a de-fined path, in order to produce a panoramic image (PAN radiogram). The rotational movement of the X-ray unit and image detector is coupled to a disk cam so that during rotation the plate is rotated about a longitudinal axis relatively to the supporting plate.
Another embodiment in U.S. Pat. No. 4,811,372 shows an X-ray device in which swivelling is effected about a stable pivot bearing having a vertical rotation axis and horizontal motion is effected with the aid of sliding guides or stable double-joint arms. A motor for effecting rotational motion drives the system to be moved and consisting of X-ray unit and image detector via a belt about the instant center, and two actuators pro-vide the necessary horizontal movement of the instant center. Rotational motion and translational motion are guided and mounted on bearings in separated elements.
WO 98 32 377 discloses rotating means having a first, stationary plate and a second, floating plate, which is supported on the first plate by at least three balls, and also means for moving said second plate. Each of the opposing surfaces of the plates exhibits as many recesses as there are balls, in which recesses the balls can roll, each ball fitting into both the recess in the stationary plate and the corresponding recess in the floating plate. The path described by the recesses is such that for each position of the floating plate there are three places where the recesses are exactly superposed and in which the respective ball is disposed, in which case the balls roll without sliding when the floating plate is moved. A disadvantage in this case is that only one such path is possible.